Magnetic clutch.



' PATENTED MAY 12,1303. E. KNOWLTONJ 1 MAGNETIC CLUTCH.APPLIOATIQNIILL'D 00?.3, 1902.

N0 MODEL.

Inventor dgar Knowlton Witnesses:

ditty.

UNITED Patented May -12, 1903.

3 ATENT OFFICE.

EDGAR KNOWLTON, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GEN- ERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

MAGN ET'ICCLUTCH.

SPECIFICATION forming part of Letters Patent No. 727,641, dated May 12,1903.

Application filed OctobrB, 1902.

To all whom it may concern:

Be it known that I, EDGAR KNOWLTON, a citizen of the United States,residing at Schen ectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Magnetic Clutches, ofwhich the following is a specification.

One of the difficulties experienced in the operation of magneticclutches is due to the fact that the current which it is necessary toemploy in the magnetizing-coils in order to draw the clutch memberstogether is sufli cient to cause the members to lock together rigidlywhen broughtin contact, owing to the large decrease in the reluctance ofthe magnetic circuit which takes place when the opposing clutch memberscontact. When one of the members is running and it is desired to couplethe other member to it, this sudden locking is quite objectionable, asit produces a jar both on the machinery which is being set in motion andon the mechanism'which is coupled to or which drives the member alreadyin motion. This is especially objectionable where synchronous motors areemployed for driving the power-shaft, as the jar tends to throw them'ontof step. To avoid this difficulty, I have provided means for reducingthe magnetizing force at the instant the clutch members contact with oneanother. One of the means which I have employed for this purposecomprises a pair of magnetizingcoils, one of which is employed to drawthe two members together andthe other of which is normallyopen-circuited,but is arranged to have its circuit completedautomatically upon the contacting of the two clutch members. This secondcoil is so constructed that its. magnetizing action is opposed to thatof the first coil. The effect, therefore, of the use of the two coils isto produce a sudden decrease in the magnetizing force when the twoclutch members come together, so that the sudden decrease in magneticreluctance which takes place at that instant is accompanied by a decrease in magnetizing force. After the members have come together themagnetizing force, and hence the force with which the clutch membersengage one another, can be 50 varied by the manipulation of a rheostatplaced in circuit with one of the magnetizing- -1 and 2, of magneticmaterial.

Serial No. 125,811. (No model.)

two clutch members are rigidly locked together one of the coils may beopen-circuited.

I- have illustrated one embodiment of my invention in the accompanyingdrawings, in which Figure l is a sectional elevation, and Figs.

2 and 3 are diagrammatical views showing the circuits of themagnetizing-coils with dif- 6o ferent positions of the switch members.

The clutch shown is of the usual form and contains two opposingdisk-shaped members These members are secured at the ends of the shafts,one of which is the drivenshaft and the other the driving-shaft. Themember 2 is provided with an annular recess 2 near its periphery, inwhich are placed two magnetizing-coils 3 and 4, which are separated-byelayerof 7o insulation 5. These coils are held inplace by a layer ofBabbitt 'or similar metal 6. Grooves are formed in the side walls of therecess, into which the Babbitt metal can run, as is clearly shown inFig. 1. A spring-finger 7, which forms one terminal of the coil 4,projects into a recess 8, formed for the purpose in the member 2 andwhich opens into the recess 2. Another spring blade or finger 9, alsolocated in the recess S'adjacent to the first spring-finger andseparated therefrom by the insulation-strip 5, is connected to one ofthe terminals of the coil 3. A sliding bolt 10, mounted in a recess 11on the front face of the member 2 and extending through into 8 therecess 8, with its head against the springfinger 9, is so proportionedas toforee the fingers or blades 7 and-9 into engagement with oneanother when the member 1 contacts with the member 2. The walls of therecess 8 are threaded to receive the screw-plug 8, which may be removedto obtain access to the switchfingers 7 and 9. The resiliency of thefinger 9 is sufficient to cause it to disengage itself from the finger 7and to move the bolt 10 out- 5 ward when the members'l'an'd2"di'sengage.

' Referring to the diagram, 12 representsa source of current supplyforthe magnetizingcoils, 13 a rheostat of the'us'ual construction, and 14the switch-arm of the rheostat. A no switch 15 is placed in the lineleading to one of the terminals ofthe coil 4.

I have not thought it necessary to illustrate the electrical connectionsbetween the coils and the switches and source of current-supply, asthese are details of construction which will be understood by any oneskilled in the art.

In operation the switch 15 is closed first, and then the switch 1a isturned to close the circuit from the coil 3 and the source of current12. This will usually cause enough current to pass through the coil 3 todraw the members 1 and 2 into contact with one another. Incase,however,current which passes is insufficient for this purpose moreresistance may be cut out of the rheostat 13 until the magnetizing forcedue to the current in the coil 3 is suiiicient to draw the memberstogether. At the instant at which the members 1 and 2 come together thebolt 10 is forced to the right, as shown in Fig. 1, which in turn forcesthe finger 9 from the position shown in Fig. 2 into contact with thefinger 7, as shown in Fig. 3, thus cutting in the coil 4. As the coil 4is so arranged that its action opposes that of the coil 3, themagnetizing force is suddenly reduced by cutting it in.

The coils 3 and 4 will usually be so proportioned that the magnetizingforce due to the joint action of the coils is merely reduced from thatof the coil 3 alone and not reversed in direction. More of theresistance of the circuit in which the coil 3 is placed may now be cutout, and the amount of slipping and the time at which the members arerigidly locked together will be governed by the operation of therheostat. When the switch-lever 14 is moved to the extreme left, asshown by the dotted position in Fig. 3, the switch 15 may be openedeither automatically by a proper mechanical connection with theswitch-arm 14: or manually by the operator. The advantages due to myconstruction will be readily appreciated by those skilled in the art.

While I have illustrated and described the best form of my inventionwhich is now known to me, I do not intend to be limited to the exactdetails of construction or arrangement which I have here shown, and itwill be un-' derstood that modifications may be made without departingfrom the spirit of my invention.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-

1. In a magnetic clutch, a pair of clutch members, means for drawingthem together, a magnetizing-coil for said members normallyopen-circuited, and automatic means for closing the circuit of said coilwhen the clutch members are drawn together.

2. In a magnetic clutch, a clutch member having a recess formed in itsface, a pair of magnetizing-coils mounted in said recess, and a switchalso mounted in said recess for connecting the two coils together.

3. In a magnetic clutch, a pair of opposed disk members adapted to bemoved into and out of engagement with one another, a pair ofmagnetizing-coils carried by one of said clutch members, a switch forconnecting said coils, and automatic means for operating said switchwhen said clutch members engage one another.

4. In a magnetic clutch, a pair of opposed disk clutch members, one ofsaid clutch members being provided with a recess, a pair ofmagnetizing-coils mounted in. said recess, a switch for connecting saidcoils also mounted in said recess, a switch-actuating member normallyprojecting from the face of said clutch member in a position to beengaged by the other clutch member when the two clutch members arebrought into contact with one another.

5. In a magnetic clutch, a pair of clutch members adapted to be drawntogether and separated, a ma netizing-coil, a second magnetizing-coil sowound as to oppose the firstmentioned coil, and means for closing thecircuit through the second coil when the clutch members are drawntogether.

6. In a magnetic. clutch, a pair of clutch members, a pair ofmagnetizing-coils therefor, means for supplying current to one of saidcoils to produce a magnetic flux through said members in one directionto draw said clutch members together, automatic means acting at theinstant at which the clutch members are drawn together for producingaflow of current in the other coil tending to produce a flux in theopposite direction.

.7. In a clutch, a pair of clutch members formed of magnetic material,said clutch members being rotatably and longitudinally movable withrespect to one another, means for causing a magnetizing force to operateupon said members to draw them together, and means for automaticallyreducing the magnetizing force when the clutch members come together.

8. In a clutch, a pair of clutch members of magnetic material rotatablyand longitudinally movable with respect to one another, a pair ofnormally open-circuited magnetizingcoils therefor, manual means forclosing the circuit of one of said coils to move said members together,and automatic means for closing the circuit of the other coil at theinstant at which the members are drawn together.

9. In a magnetic clutch, a pair of clutch members adapted to be drawntogether and separated, means for producing a magnetic flux for drawingsaid members together, and means for preventing an objectionableincrease in said flux when the clutch members come together.

In witness whereof I have hereunto set my hand this 2d dayof October,1902.

EDGAR KNOWLTON.

IVitn esses:

BENJAMIN B. IIULL, HELEN ORFORD.

